Solid capacitor and manufacturing method thereof

ABSTRACT

A solid capacitor and the manufacturing method thereof are disclosed. The solid capacitor consists of a dielectric layer and two electrodes. A plurality of holes formed by an opening process is disposed on surface of the dielectric layer. The two electrodes connect with the dielectric layer by the holes. By means of a plurality of high temperature volatile matters, the plurality of holes is formed on surface of the dielectric layer during sintered process. The holes are connected with the outside so as to increase surface area of the dielectric layer and further the capacity is increased. And the solid capacitor stores charge by physical means. Moreover, the solid capacitor can be stacked repeatedly to become a multilayer capacitor.

BACKGROUND OF THE INVENTION

The present invention relates to a capacitor, especially to a solidcapacitor that increases the capacity by means of larger surface area ofthe dielectric layer thereof. Moreover, the solid capacitor inaccordance with the present invention can be stacked repeatedly so as toform a multilayer capacitor.

A capacitor is an energy storage component applied in circuits fortuning, filtering, coupling, by-pass, energy conversion and delay. Mostcommon used capacitors are electrolytic capacitors, mica capacitors,ceramic capacitors and vitreous-enamel capacitor. The names refer to thetype of dielectric that is used within the capacitor. capacitor typesstructure and features aluminum An aluminum cylinder works as aelectrolytic cathode with liquid electrolyte therein capacitor and acurved aluminum piece is used as an anode. The flow of direct currentcauses an insulating metal oxide to grow out of and into the surface ofthe anode. The metal oxide is used as dielectric. The advantage ofelectrolytic capacitors is the high capacity per unit volume. Thedisadvantage of electrolytic capacitors is the non-ideal, lossycharacteristics and poor stability. It is used for signal coupling. Inusage, please note that the voltage should not be applied in the reversedirection. paper capacitor Two metal foils as electrodes are clipped oninsulated paper and the assembly can be rolled up to form a cylinderthat is enclosed inside a metal housing or insulated material such assealing wax, ceramic or vitreous-enamel. The package is smaller withhigher capacitance. Due to high inherent inductance and loss ofcapacitor, the device is suitable for being applied to low frequencycircuit. metallized The device basically has the same paper capacitorstructure with paper capacitors while a metal membrane is used insteadof metal foil. Its features are small volume and higher capacitance,generally applied to low-frequency circuit. oil impregnated Byimpregnating the paper with special paper capacitor oil, tolerance ofthe capacitor is improved. It features on high capacity and widetolerance. However, the volume of the device is quite large.vitreous-enamel The dielectric material is capacitor vitreous-enamel. Ithas advantages of ceramic capacitors while the volume is smaller. Itwithstands high temperature. ceramic The dielectric is ceramic and thecapacitor plates are made from ceramic base with silver membrane. Itsfeatures are small volume, good thermostability, higher insulationresistance but low capacity. Thus it is used for high frequency circuit.The ferroelectric ceramic capacitor has higher capacity while the lossand temperature coefficient are higher. Thus it is applied to lowfrequency circuit. film capacitor This capacitor has the same structurewith the paper capacitor. The dielectric of the capacitor is polyesteror polystyrene. The polyester capacitor has higher dielectric constant,small volume, high capacity, and good stability thus is suitable forbypass capacitors. While the polystyrene capacitor has small loss, highinsulation resistance but high temperature coefficient. This capacitoris suitable for high frequency circuit. mica capacitor The silverelectrodes or metal foil are plated directly onto the mica dielectric.Several layers of electrodes and mica are laminated and then are castinside the phenolic resin or sealed inside the epoxy. Its properties arelow loss of dielectric, high insulation resistance, low temperaturecoefficient and it is suitable for high frequency circuit. tantalum orTantalum or niobium is used as niobium positive electrode and dilutedsulfuric electrolytic acid works as negative electrode while capacitordielectric is oxide membrane on surface of the tantalum or niobium. Ithas small volume, high capacity, stable performance, long life, highinsulation resistance, and good thermostability. Thus it is applied toequipments with higher requirements of capacitors. semi-variable It'salso called trimmer capacitor. The capacitor device consists of twopieces or two sets of metal spring with dielectric therebetween. Thedistance or area between two metal springs changes while tuning. Thedielectric can be air, ceramic, mica or membrane. variable It isconstructed by a set of immobile capacitor plates called stator, andanother set of plates, connected to a common axis, called rotor and itscapacity changes according to rotation of the rotor. The two-foldcapacitors are two capacitors whose rotors share the common axis. Thedielectric of such capacitor can be air or polystyrene. Capacitors withair dielectric with features of large volume and small loss are used inthe electron tube radios. The variable capacitor with polystyrenedielectric is a compact sealed capacitor, mostly used in the transistorradio.

Solid capacitors with dielectric layer made from ceramic material withhigh dielectric constant have features of environmental protection, lowimpedance, high thermostability, withstanding high ripple current andhigh reliability. Compared with traditional electrolytic capacitors,solid capacitors have higher stability thus explosion may occur lessfrequently.

The most common solid capacitor is multilayer ceramic capacitor (MLCC)manufactured by suspending ceramic powders in liquid and casting into athin green sheet with thickness from 20 um to 5 um or even thinner. Thenmetal electrodes are sieved (screen) printed onto the sheets which arelater stacked with sheets without electrodes alternately to form alaminated structure. After being sintered at high temperature, thedevice becomes a ceramic sinter that provides an extremely high capacityin a small volume. At last, surface of silver terminal electrode isplated with nickel, tin and lead and then the multilayer ceramic issoldered directly onto the printed circuit board.

The present invention provides a solid capacitor that improvesdisadvantages of electrolytic capacitors and increases capacity.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to provide asolid capacitor and the manufacturing method thereof. The capacitorincludes a dielectric layer with a plurality of holes on surface thereofand two electrodes arranged on two sides of the dielectric layerrespectively. The electrodes contact the holes. Due to the plurality ofholes on surface of the dielectric layer, the surface area of thedielectric layer is increased so that the capacity of the solidcapacitor is improved.

It is another object of the present invention to provide a solidcapacitor and the manufacturing method thereof. While manufacturing thecapacitor, a plurality of high temperature volatile matters is mixed onsurface of the dielectric layer and part of the high temperaturevolatile matters is vapored or volatilized during sintering process ofthe dielectric layer so as to form a plurality of holes on surface ofthe dielectric layer. Thus the surface area of the dielectric layer isincreased and the capacity of the solid capacitor is also gettinghigher.

It is a further object of the present invention to provide a solidcapacitor and the manufacturing method thereof that generate amultilayer capacitor by stacking the capacitor repeatedly so as toincrease the capacity.

In order to achieve above objects, a solid capacitor and a manufacturingmethod thereof are disclosed. The solid capacitor is composed by adielectric layer and two electrodes. A plurality of holes formed by anopening process is disposed on surface of the dielectric layer. The twoelectrodes are connected with the dielectric layer through the holes.Due to the enlarged surface area of the dielectric layer, the capacityof the capacitor is increased. The solid capacitor stores charge byphysical means.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present inventionto achieve the above and other objects can be best understood byreferring to the following detailed description of the preferredembodiments and the accompanying drawings, wherein

FIG. 1A to FIG. 1D are schematic drawings showing structure of anembodiment in accordance with the present invention;

FIG. 1E is a schematic top view showing an embodiment of the presentinvention with holes coated with conductive object;

FIG. 2 is a schematic drawing showing structure of another embodiment inaccordance with the present invention;

FIG. 3 is a curve chart showing capacity of capacitors with and withoutholes under different frequencies;

FIG. 4A to FIG. 4D are schematic drawings showing structure of amultilayer capacitor in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides a solid capacitor for improvingdisadvantages of conventional capacitors such as easily explosions andenvironmental pollutions by means of larger surface area for increasingstored charge. And the solid capacitor is a device that stores thecapacity of a physical system.

Refer from FIG. 1A to FIG. 1D, structure of a solid capacitor 1 inaccordance with the present invention is disclosed. In the beginning, adielectric green tape 10 is sintered into a dense dielectric layer 100.The temperature for sintering ranges from 600 degrees Celsius to 1700degrees Celsius. Then two sides of the dense dielectric layer 100 arecoated with a plurality of dielectric 20 that is mixture of a pluralityof high temperature volatile matter 30 or a plurality of conductiveobjects. The dense dielectric layer 100 and the dielectric 20 aresintered at an operating temperature of 300 to 1700 degrees so as tomake the dielectric 20 form a loose dielectric layer 200. After the hightemperature volatile matter 30 being volatilized, a plurality of holes300 connected with the outside are formed on surface of tow sides of theloose dielectric layer 200. The diameter or width of the hole 300 isbetween 1 nm˜100 μm while the range of 10 nm˜10 μm is preferred. And thebest range is from 5 nm to 50 μm. Therefore, the loose dielectric layer200 with large surface area is formed. Moreover, two sides of the loosedielectric layer 200 are connected with two electrodes 400 respectivelythrough the holes 300. The electrodes 400 are formed on surface of theloose dielectric layer 200 by one of electroplating, electrolessplating, sputtering, spin-coating, coating, printing and chemical vapordeposition (CVD) or by combinations of above techniques.

The density ratio of the loose dielectric layer 200 and the densedielectric layer 100 ranges from 0.05 to 0.95 while the range between0.1 and 0.9 is preferred and the best ratio ranges from 0.15 to 0.85.The material of the dielectric 20 and the dielectric green tape 10 canbe the same or different. The material is selected from ceramicdielectric layer, high molecular dielectric layer, and glass dielectriclayer or various combinations of above material.

The holes 300 are formed on the loose dielectric layer 200, the holes300 are connected to the outside, not the holes inside the loosedielectric layer 200 without contact the outside. Moreover, once thedielectric 20 having the high temperature volatile matter 30, the hightemperature volatile matter 30 can be carbon, organics or theircombinations. After being sintered, the holes 300 of the loosedielectric layer 200 is coated with the conductive object 500, as shownin FIG. 1E. The conductive object 500 can be carbon that works as anelectrical connection between the electrodes 400 and the loosedielectric layer 200. The solid capacitor according to the presentinvention stores charge by physical means.

Furthermore, refer to FIG. 2 & FIG. 1C, the present invention furtherprovides another manufacturing method to produce the solid capacitor. Atfirst, a dielectric green tape 40 including a first dielectric layer 42and two second dielectric layers 44 is formed. The two second dielectriclayers 44 mixed with a plurality of high temperature volatile matter 30or a plurality of conductive objects are disposed on two sides of thefirst dielectric layer 42. The dielectric green tape 40 is sintered soas to make the first dielectric layer 42 become the dense dielectriclayer 100. Also the high temperature volatile matter 30 is volatilizedto form the holes 300 so that the second dielectric layers 44 form theloose dielectric layers 200. The first dielectric layer 42 and thesecond dielectric layers 44 are sintered into dense and loose structurerespectively due to different material they made from. The followingmanufacturing processes are the same with above descriptions.

Moreover, once the second dielectric layers 44 is mixed with the hightemperature volatile matter 30, the high temperature volatile matter 30can be carbon, organics or their combinations. After being sintered, theloose dielectric layer 200 is generated and the holes 300 thereon shouldbe coated with the conductive object 500 for providing an electricalconnection between the electrodes and the loose dielectric layers, asshown in FIG. 1E.

An embodiment is taking as an example for explanation of the presentinvention:

Experiment group of the present invention: Taking a dielectric greentape and press it under pressure of 100 Kg/cm², sintered at 1350 degreesCelsius, the operating time is 2 hours. Thus a dense dielectric layer isformed and two outer sides of the dense dielectric layer are coated withdielectric material and carbon fiber (C.F.) at the ratio of 300:1. Afterbeing dried at 70 degrees Celsius for 10 minutes, the invention issintered at a temperature of 1350 degrees so as to form a loosedielectric layer with the thickness of 0.09 mm.

Control group without the loose dielectric layer: The green tape ispressed under 100 Kg/cm², at a temperature of 1350 degrees Celsius, theoperating time is 2 hours. Capacitance Frequency Experimental Control(Hz) group group  10K 4805 1874  50K 3480 1766  100K 3137 1760  500K2781 1736 1000K 2462 1650

Refer to FIG. 3, the curves shows capacity of capacitors with or withoutholes under different frequencies respectively. As shown in figure, thefirst curve S1 and the secondary curve S2 represent capacity ofcapacitors with and without holes respectively under differentfrequencies. Compared the curve S1 with the curve S2, it is obvious thatthe capacitor with holes has higher capacity than the capacitor withoutholes under different frequencies.

In addition, a solid capacitor according to the present invention can bea multilayer capacitor for demanding of higher capacity. As shown fromFIG. 4A to FIG. 4D, firstly, the solid capacitor 1 in accordance withthe present invention is manufactured as structure in FIG. 4A, thelength of two loose dielectric layers 200 of the solid capacitor 1 areshorter than that of the dense dielectric layers 100 and a firstelectrode 210 as well as a second electrode 220 is disposed thereof.This is a basic unit. Then a first solid capacitor 600 is arranged on asecond solid capacitor 700 reversely and the second electrode 220 iselectrically connected with a third electrode 710 of the second solidcapacitor 700, as shown in FIG. 4B. Thus a repeated unit 800 is formed.

Then the repeated units 800 are stacked repeatedly. A first outerelectrode 810 and a second outer electrode 820 are arranged on twooutsides. The first outer electrode 810 is electrically connected withthe first electrode 210 and a fourth electrode 720 of the seconddielectric layer while the second outer electrode 820 is electricallyconnected with the second electrode 220 and the third electrode 710 soas to form a multilayer capacitor.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details, and representative devices shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A solid capacitor comprising: at least one dense dielectric layer; atleast two loose dielectric layer disposed on two outer sides of thedense dielectric layer while a plurality of holes connected with theoutside are mounted on surface of the loose dielectric layer; and twoelectrodes are disposed on outer sides of the two loose dielectric layerrespectively and the electrodes contact the loose dielectric layer bythe plurality of holes.
 2. The solid capacitor as claimed in claim 1,wherein ratio of the density of the loose dielectric layer to that ofthe dense dielectric layer ranges from 0.05 to 0.95.
 3. The solidcapacitor as claimed in claim 2, wherein ratio of the density of theloose dielectric layer to that of the dense dielectric layer preferablyranges from 0.1 to 0.9.
 4. The solid capacitor as claimed in claim 3,wherein ratio of the density of the loose dielectric layer to that ofthe dense dielectric layer best ranges from 0.15 to 0.85.
 5. The solidcapacitor as claimed in claim 1, wherein the dense dielectric layer is aceramic dielectric layer, a high molecular dielectric layer, a glassdielectric layer or various combinations of above dielectric layers. 6.The solid capacitor as claimed in claim 1, wherein the loose dielectriclayer is a ceramic dielectric layer, a high molecular dielectric layer,a glass dielectric layer or various combinations of above dielectriclayers.
 7. The solid capacitor as claimed in claim 1, wherein diameteror width of the holes of the loose dielectric layer is from 1 nm to 100μm.
 8. The solid capacitor as claimed in claim 7, wherein diameter orwidth of the holes of the loose dielectric layer is preferably from 10nm to 10 μm.
 9. The solid capacitor as claimed in claim 8, whereindiameter or width of the holes of the loose dielectric layer is bestfrom 5 nm to 50 μm.
 10. The solid capacitor as claimed in claim 1,wherein the loose dielectric layer is mixed with at least one conductiveobject.
 11. The solid capacitor as claimed in claim 1, wherein surfaceof the holes is coated with at least one conductive object.
 12. Thesolid capacitor as claimed in claim 10, wherein the conductive object iscarbon.
 13. The solid capacitor as claimed in claim 11, wherein theconductive object is carbon.
 14. The solid capacitor as claimed in claim1, wherein the solid capacitor stores charge in a physical way.
 15. Amanufacturing method for a solid capacitor comprising the steps of:forming at least one dense dielectric layer having at least one loosedielectric layer on two outer sides thereof respectively and a pluralityof holes connected with the outside on surface thereof; and forming anelectrode on respective outer side of the loose dielectric layer; theelectrode contacts the loose dielectric layer through the holes.
 16. Themanufacturing method as claimed in claim 15, wherein on step of formingat least one dense dielectric layer having at least one loose dielectriclayer one two outer sides thereof respectively, the loose dielectriclayer is mixed with a plurality of conductive objects.
 17. Themanufacturing method as claimed in claim 15, wherein on step of formingat least one dense dielectric layer having at least one loose dielectriclayer one two outer sides thereof respectively, a plurality ofconductive objects are coated on surface of the holes.
 18. Themanufacturing method as claimed in claim 15, wherein the step of formingat least one dense dielectric layer having at least one loose dielectriclayer one two outer sides thereof respectively further comprising thesteps of: providing at least one dielectric green tape; sintering thedielectric green tape to form the dense dielectric layer; coating aplurality of dielectric on two outer sides of the dense dielectriclayer; and sintering the dense dielectric layer and the dielectric so asto make the dielectric form the loose dielectric layer.
 19. Themanufacturing method as claimed in claim 18, wherein on step ofsintering the dielectric green tape to form the dense dielectric layer,the operating temperature is from 600 degrees Celsius to 1700 degreesCelsius.
 20. The manufacturing method as claimed in claim 18, wherein onstep of sintering the dense dielectric layer and the dielectric, theoperating temperature is from 300 degrees Celsius to 1700 degreesCelsius.
 21. The manufacturing method as claimed in claim 18, wherein onstep of coating a plurality of dielectric on two outer sides of thedense dielectric layer, the dielectric is mixed with a plurality ofconductive objects.
 22. The manufacturing method as claimed in claim 18,wherein the method further comprising a step after the step of sinteringthe dense dielectric layer and the dielectric so as to make thedielectric form the loose dielectric layer: coating a plurality ofconductive objects on surface of the holes of the loose dielectriclayer.
 23. The manufacturing method as claimed in claim 15, wherein thestep of forming at least one dense dielectric layer having at least oneloose dielectric layer one two outer sides thereof respectively furthercomprising the steps of: forming at least one dielectric green tapehaving at least one first dielectric layer and at least two seconddielectric layers while the second dielectric layers are arranged on twoouter sides of the first dielectric layer and the second dielectriclayer is mixed with a plurality of high temperature volatile matters;and sintering the dielectric green tape so as to make the firstdielectric layer form the dense dielectric layer and the hightemperature volatile matters are volatilized for forming the holes so asto make the second dielectric layer become the loose dielectric layer.24. The manufacturing method as claimed in claim 23, wherein on step ofsintering the dielectric green tape, the operating temperature is from300 degrees Celsius to 1700 degrees Celsius.
 25. The manufacturingmethod as claimed in claim 23, wherein the high temperature volatilematter is carbon, organics or combinations of carbon and organics. 26.The manufacturing method as claimed in claim 15, wherein on step offorming an electrode on respective outer side of the loose dielectriclayer, the electrode is formed on outer side of the loose dielectriclayer by electroplating, electroless plating, sputtering, spin-coating,coating, printing, chemical vapor deposition (CVD) or combinations ofabove techniques.
 27. A solid capacitor comprising: at least onedielectric layer having a plurality of holes that are connected with theoutside and disposed on surface of two outer sides thereof; and twoelectrodes arranged on outer side of the dielectric layer and contactwith the holes; wherein the solid capacitor stores charge in a physicalway.
 28. The solid capacitor as claimed in claim 27, wherein diameter ofthe holes is from 0.01 nm to 10 μm.
 29. The solid capacitor as claimedin claim 27, wherein the dielectric layer is mixed with a plurality ofconductive objects.
 30. The solid capacitor as claimed in claim 27,wherein surface of the holes is coated with a plurality of conductiveobjects.
 31. The solid capacitor as claimed in claim 29, wherein theconductive object is carbon.
 32. The solid capacitor as claimed in claim30, wherein the conductive object is carbon.
 33. A solid capacitorcomprising: a dielectric layer having at least one dense dielectriclayer and at least two loose dielectric layers on two outer sides of thedense dielectric layer; a plurality of holes connected with the outsideare formed by an opening process on surface of two outer sides of thedielectric layer; and two electrodes arranged on two outer sides of thedielectric layer and in contact with the holes.
 34. The solid capacitoras claimed in claim 33, wherein the opening process for the holes is asintering process.
 35. The solid capacitor as claimed in claim 33,wherein ratio of the density of the loose dielectric layer to that ofthe dense dielectric layer ranges from 0.05 to 0.95.
 36. The solidcapacitor as claimed in claim 33, wherein ratio of the thickness of therespective loose dielectric layer to that of the dielectric layer rangesfrom 0.01 to 0.45.
 37. The solid capacitor as claimed in claim 33,wherein ratio of the thickness of the dense dielectric layer to that ofthe dielectric layer ranges from 0.1 to 0.98.
 38. The solid capacitor asclaimed in claim 37, wherein diameter of the holes is from 0.01 nm to 10μm.
 39. The solid capacitor as claimed in claim 33, wherein thedielectric layer is mixed with a plurality of conductive objects. 40.The solid capacitor as claimed in claim 33, wherein surface of the holesis coated with a plurality of conductive objects.
 41. The solidcapacitor as claimed in claim 39, wherein the conductive object iscarbon.
 42. The solid capacitor as claimed in claim 40, wherein theconductive object is carbon.
 43. The solid capacitor as claimed in claim33, wherein the solid capacitor stores charge in a physical way byassembly of the two electrodes and the dielectric layer.
 44. A solidcapacitor comprising: at least a first dielectric layer with a pluralityof holes on surface of two outer sides thereof while the holes areconnected with the outside; a first electrode and a second electrode aredisposed on outer sides of the dielectric layer respectively; theelectrodes are in contact with the holes; and at least a seconddielectric layer with a plurality of holes on surface of two outer sidesthereof while the holes are connected with the outside; a thirdelectrode and a fourth electrode are disposed on outer sides of thedielectric layer respectively; the electrodes are in contact with theholes; the second dielectric layer is arranged reversely over the firstdielectric layer while the second electrode contacts the thirdelectrode; wherein the solid capacitor stores charge in a physical way.45. The solid capacitor as claimed in claim 44, wherein the firstdielectric layer and the second dielectric layer respectively having atleast one dense dielectric layer and at least two loose dielectriclayers.
 46. The solid capacitor as claimed in claim 44, wherein diameterof the holes ranges from 0.01 nm to 10 μm.
 47. The solid capacitor asclaimed in claim 44, wherein the dielectric layer is mixed with aplurality of conductive objects.
 48. The solid capacitor as claimed inclaim 44, wherein surface of the holes is coated with a plurality ofconductive objects.
 49. The solid capacitor as claimed in claim 47,wherein the conductive object is carbon.
 50. The solid capacitor asclaimed in claim 48, wherein the conductive object is carbon.
 51. Thesolid capacitor as claimed in claim 44, wherein the solid capacitors arestacked repeatedly so as to form a multilayer capacitor.
 52. The solidcapacitor as claimed in claim 51, wherein the solid capacitors arestacked in odd number.
 53. The solid capacitor as claimed in claim 51,wherein the solid capacitors are stacked in even number.
 54. The solidcapacitor as claimed in claim 51, wherein the solid capacitor furthercomprising: a first outer electrode arranged on one side of the firstdielectric layer and the second dielectric layer and electricallyconnected with the first electrode and the fourth electrode; and asecond outer electrode arranged on the other side of the firstdielectric layer and the second dielectric layer and electricallyconnected with the second electrode and the third electrode.